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I 


L161—  O-1096 


ACE 

JUN  1  6  2005 


UNiVERSJTYOHLUNOIS 


UNIVERSITY  OF  ILLINOIS       .'  - 

Agricultural  Experiment  Station. 


URBANA,  JUNE,  1903. 


BULLETIN   No.  86. 


CLIMATE   OF  ILLINOIS. 


BY  J.  G.  MOSIER,  B.  S.,  CHIEF  ASSISTANT  IN  SOIL  PHYSICS. 


This  state  lies  with  its  northern  boundary  2V5  south  of  the  center  of 
the  north  temperate  zone,  while  the  southern  extremity  is  only  13j° 
from  the  torrid  zone.  It  extends  over  5£°  of  latitude,  or  about  380 
miles.  It  is  situated  mostly  in  the  belt  of  hot  summers  and  cold  winters, 
but  in  the  southern  part  the  winters  are  temperate.  The  altitude  of 
the  state  above  sea  varies  between  320  feet  in  the  extreme  southern  part 
to  1,257  feet  in  Jo  Daviess  County,  the  highest  point  in  the  state.  The 
Ozark  Ridge,  extending  east  and  west  across  the  southern  end,  reaches 
a  height  of  1,046  feet  in  the  northwest  of  Pope  County.  This  range  of 
altitude  is  too  small  to  affect  the  climate  to  any  marked  extent,  although 
the  Ozark  Ridge  does  seem  to  exert  some  influence  over  the  rainfall. 

The  state  lies  entirely  within  the  belt  of  prevailing  westerly  winds 
with  its  accompanying  cyclones  and  anticyclones.  To  these  "lows"  and 
"  highs,"  as  they  are  commonly  designated  by  the  weather  forecaster,  is 
due  the  peculiar  climate  of  the  state.  Our  weather  changes  are  almost 
entirely  caused  by  the  passage  of  these  across  the  country,  and  their 
importance  requires  more  than  a  passing  notice  here. 

CYCLONES,  OR  Lows;  ANTICYCLONES,  OR  HIGHS. 
A  cyclone,  or  "low,"  is  an  area  having  an  atmospheric  pressure  lower 
than  the  normal,  due  to  the  rising  of  air  in  that  locality.     Throughout 
this  area  the  top  of  the  column  of  mercury  in  the  barometer  (used  in 

45 


46 


BULLETIN  No.  86. 


[June, 


measuring  the  pressure  of  the  air)  is  lower  than  normal,  hence  the  word 
"  low. "  A  "  high  "  is,  of  course,  an  area  where  the  atmospheric  pressure 
is  higher  than  normal  and  the  term  anticyclone  is  sometimes  used  to 
mean  the  same  thing. 

Low  pressure  areas  are  very  large  whirlwinds  from  a  few  hundred  to  as 
much  as  two  thousand  miles  in  diameter.  These  lows,  or  cyclones,  are  to 
be  distinguished  from  the  small,  very  violent  whirlwinds  or  tornadoes 
that  are  so  much  dreaded.  The  term  cyclone  is  very  frequently  erro- 
neously applied  to  tornadoes  but  in  the  cyclone  proper  the  wind  rarely 
attains  a  velocity  sufficient  to  do  much  damage.  The  usual  move- 
ment of  03  clones  is  in  an  easterly  direction,  at  from  twenty  to  thirty 
miles  an  hour.  During  the  cooler  season  of  the  year  they  pass  more 
rapidly  and  are  better  defined  than. in  summer. 


1903.J  .  CLIMATE  OF  ILLINOIS.  47 

The  approach  of  a  cyclone  is  usually  indicated  by  the  changing  of 
the  wind  to  a  southerly  or  an  easterly  direction,  by  the  appearance  of 
white,  stringy,  or  fibrous  clouds,  or  by  a  general  haziness  that  produces 
a  halo  or  circle  around  the  sun  or  moon. 

Plate  I  is  a  diagram  of  a  "  low  "  as  it  is  represented  on  weather  maps. 
The  large  arrow  represents  the  direction  of  movement.  The  heavy 
curved  lines  are  isobars  and  are  drawn  through  places  having  the  same 
atmospheric  pressure.  The  meaning  of  the  term  "low"  may  be  read- 
ily seen  from  this.  The  dotted  lines  are  isotherms,  or  lines  drawn 
through  places  having  the  same  temperature.  Small  arrows  point  in 
the  direction  toward  which  the  wind  is  blowing.  The  circles  and  letters 
indicate  the  condition  of  the  weather;  as,  o,  clear;  e,  partly  cloudy; 
®,  cloudy.;  R,  rain;  S,  snow. 

One  of  the  most  important  and  noticeable  changes  that  occurs  during 
the  passage  of  a  cyclone  is  the  shifting  of  the  wind  with  its  accompany- 
ing change  in  temperature.  Let  us  notice  some  of  the  changes  that  take 
place  as  the  different  parts  of  the  cyclone  pass  over  different  places. 
Let  us  assume  a  place,  so  situated  that  the  southern  part  of  the  storm 
passes  over  it,  along  the  line  A  B.  (See  Plate  I.) 

Since  a  cyclone  is  a  whirling  storm  the  wind  will  not  blow  directly  in 
toward  the  center  of  the  low,  but  spirally,  as  could  be  shown  by  producing 
one  of  the  small  arrows  so  as  to  have  it  approach  the  center  forming  a 
spiral.  At  A  in  the  "high,"  the  wind  will  blow  from  the  north,  but 
as  the  storm  approaches  it  will  shift  to  the  south  or  southeast,  and  at 
the  same  time  the  temperature  will  begin  to  rise.  As  the  storm  passes 
eastward  the  wind  will  change  to  southwest,  to  west,  and  then  to  north- 
west, and  the  temperature  will  become  lower  until  25°  is  reached  at  B. 
If  the  storm  pass  over  a  place  along  the  line  C  D,  the  wind  will  blow 
from  the  southeast  till  the  center  of  the  storm  is  reached,  when  it  will 
suddenly  change  to  the  northwest  with  a  lowering  of  temperature  until  20° 
or  lower  is  reached.  If  the  northern  part  of  the  cyclone  pass  over  a 
place  along  the  line  E  F,  the  wind  will  blow  from  an  easterly  direction, 
but  as  the  center  of  the  storm  passes  to  the  south  there  will  be  a  gradual 
shifting  of  the  wind  to  the  north  and  northwest  with  a  lowering  of  tem- 
perature. The  easterly  winds  of  this  part  of  the  storm  are  usually 
accompanied  by  cold,  steady  rains  in  the  warmer  seasons,  and  by  heavy 
snows  in  winter.  The  rainfall  in  the  southeast  part  of  a  cyclone  is  usually 
in  the  form  of  local  showers,  frequently  very  heavy.  As  a  general  thing, 
little  rain  or  snow  falls  after  the  center  of  the  low  is  past  and  the  wind 
has  shifted  to  the  west  or  northwest.  Clearing  weather  usually 
follows  the  passage  of  the  center,  and  the  rear  of  the  storm  is  marked 
by  cool,  clear  weather.  The  directions  of  the  wind  given  above  are 
greatly  modified  by  the  fact  that  the  cyclone  frequently  comes  from  the 
northwest  to  about  the  Mississippi  Valley  and  then  turns  to  the  northeast. 


48 


BULLETIN  No.  86. 


[June, 


SOURCES  OF  DATA. 

The  data  for  this  bulletin  was  very  largely  obtained  from  the  records 
and  publications  of  the  Weather  Bureau,  and  I  desire  to  thank  the 
directors  of  the  stations,  and  especially  the  Chief  of  the  Weather  Bureau, 
for  so  kindly  furnishing  the  data  desired.  The  records  for  some  of  the 
counties  are  fragmentary,  and  in  many  cases  short,  and  eleven  have  no 
records;  but  the  records  obtained  are  so  well  distributed  that  a  good 
average  for  the  state,  districts,  and  a  very  large  number  of  counties 
has  been  obtained.  For  counties  without  records  the  averages  have 
been  obtained  by  taking  the  data  from  surrounding  counties.  In  a  few 
cases  records  have  been  taken  from  stations  just  outside  of  the  state,  as 
Dubuque,  Davenport,  and  Keokuk,  Iowa;  Hannibal  and  St.  Louis, 
Missouri;  Paducah,  Kentucky;  Vincennes  and  Terre  Haute,  Indiana; 
and  Beloit,  Wisconsin. 

DISTRICTS. 

For  convenience,  the  state  has  been  divided  into  three  districts,  or 
sections,  the  northern,  central,  and  southern.  The  boundary  between  the 
northern  and  central  sections  is  formed  by  the  county  lines  lying  nearest 
the  parallel  of  40°  40 ' ,  and  that  between  the  central  and  southern  sections 
by  the  county  lines  nearest  the  parallel  of  39°. 

TABLE  2. — AVERAGE  RAINFALL  BY  YEARS   FOR  THE  DISTRICTS  AND  THE  STATE — 

INCHES. 


District. 

1872. 

1873. 

1874. 

1875. 

1876. 

1877. 

1878. 

1879. 

1880. 

1881. 

1882. 

Northern  .... 
Central  

35.15 
32.65 
30.05 

34.72 
43.17 
49.51 

27.20 
32.17 
46.82 

34.85 
43.22 

48.48 

40.22 
48.67 
54.03 

38.87 
46.12 
43.23 

34.92 
43.18 
43.25 

29.70 
22.85 
43.08 

37.09 
38.02 
46.30 

42.64 
48.11 
36.73 

39.23 
44.91 
55.68 

Southern   .... 

Av.  for  state  .  . 

33.32 

40.35 

32.45 

39.23 

45.47 

41.32 

41.07 

33.03 

39.51 

41.94 

45.01 

District. 

1883. 

1884. 

1885. 

1886. 

1887. 

1888. 

1889. 

1890. 

1891. 

1892. 

1893. 

Northern  .... 
Central.    .  . 

40.72 
43.40 
51.93 

40.07 
39.56 
47.55 

38.56 
40.93 
41.34 

28.88 
36.12 
38.54 

31.36 
33.27 
34.64 

31.77 
41.51 
42,13 

31.27 
36.80 
40.96 

34.09 
32.82 
48.68 

21.46 
31.09 
36.10 

41.35 
41.27 
39.78 

29.90 
39.94 
41.40 

Southern  

Av.  for  state  .  . 

45.06 

42.32 

40.02 

34.01 

32.71 

38.21 

35.88 

38.33 

29.62 

40.02 

34.11 

District 

1894. 

1895. 

1896. 

1897. 

1898. 

1899. 

1900. 

1901. 

1902. 

Av. 

Northern  .   .  . 

26.77 
28.36 
31.77 

28.04 
32.75 
34.91 

34.76 
37.75 
39.23 

29.16 
37.03 
45.63 

41.6529.03 
45.2934.64 
53.6238.91 

34.33 
35.09 

38.  2C 

22.95 
26.19 
30.34 

47.22 
41.56 
35.03 

33.48 
38.01 
42.19 

Central  

Southern  

Average  for  state  .  .  . 

28.33 

31.17 

36.62 

36.48 

47.39 

33.91 

35.70 

25.00 

41.58 

37.39 

1903.] 


CLIMATE  OF  ILLINOIS. 


49 


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CLIMATE  OF  ILLINOIS. 


51 


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WWVERfiiTY  OF  ILLINOIS 
LIBRARY 


52 


BULLETIN  No.  86. 


[June, 


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CLIMATE  OF  ILLINOIS. 


53 


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54 


BULLETIN  No.  86. 


[June, 


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1903.] 


CLIMATE  OF  ILLINOIS. 


55 


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56 


BULLETIN  No.  86. 


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1903.] 


CLIMATE  OP  ILLINOIS. 


57 


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58 


BULLETIN  No.  86. 


[June, 


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1903.] 


CLIMATE  OF  ILLINOIS. 


59 


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BULLETIN  No.  86. 


[June, 


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1903.]  CLIMATE  OF  ILLINOIS. 

TABLE  4. — AVERAGE  MONTHLY  RAINFALL  IN  INCHES. 


61 


District. 

d 

03 

rt 

JD 
.« 

fa 

§ 

s 

^ 

a 

<3 

>> 

<p 

3 

1-5 

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3 

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&, 

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5 

O 

o 
fc 

6 
I 

Northern  '  ' 

1   97 

1   94 

2  7?, 

9  51 

4  05 

3  85 

3  67 

?  97 

3  ?1 

2  04 

?  ?3 

1    81 

Central  

?,  7,1 

?  ?8 

8  04 

8  37 

4  9.6 

4  ?? 

3  53 

2  69 

3  ?7 

2  04 

9  89 

?  94 

Southern    .    .  . 

?,  85 

?,  8? 

4  4? 

3  53 

4  06 

4  ?,Q 

3  37 

2  58 

?  74 

2  25 

3  57 

2  80 

Average  for  State  .-. 

9  30 

?  ?M 

3  ?8 

3  OS 

4  13 

4  10 

3  54 

?  77 

3  11 

2  09 

?  8? 

9   ??| 

RAINFALL  OF  THE  STATE. 

NORTHERN  DISTRICT.. — The  word  rainfall,  as  used  in  this  bulletin, 
includes  both  rain  and  snow.  The  average  for  both  state  and  districts 
has  been  obtained  from  observations  made  since  1872  and  extending  over 
a  period  of  thirty-one  years.  The  records  previous  to  that  date  are  too 
fragmentary  for  calculating  yearly  averages.  The  average  rainfall  for  the 
northern  district  is  33.48  inches.  Since  1872,  thirteen  years  have  been 
below  the  normal,  the  lowest  being  21.46  inches  in  1891,  and  the  next 
22.95  inches  in  1901.  The  greatest  rainfall  for  thir  district  was  in  1902, 
47.22  inches  and  the  next  in  1898,  41.65  inches.  Of  the  entire  rainfall 
about  17.4  percent  falls  in  winter,  28.1  percent  in  spring,  31.9  percent  in 
summer-,  and  22.6  percent  in  autumn.  May  is  the  wettest  month,  with 
an  average  of  4.05  inches,  and  is  followed  by  June,  with  3.85  inches. 
December  has  least  rainfall,  1.81  inches.  February  and  January  coming 
next  with  1.94  and  1.97  inches.  The  rainfall  is  very  irregular,  as  is 
shown  by  Table  3.  A  month  with  a  rainfall  of  not  more  than  two 
inches  may  usually  be  considered  a  dry  month,  especially  in  spring  or 
summer  when  the  growing  crops  need  a  bountiful  supply  of  moisture. 
During  the  eighteen  years  that  observations  have  been  taken  at  Syca- 
more, DeKalb  County,  seven  Aprils,  four  Mays,  and  seven  Junes  have 
had  less  than  two  inches  of  rainfall;  that  is,  have  been  dry. 

CEATRAL  DISTRICT. — The  central  district  has  an  average  rainfall  of 
38.01  inches.  Since  1872,  fifteen  years  have  been  below  the  average, 
the  lowest  being  22.85  inches  in  1879,  the  next,  26.19  inches  in  1901. 

The  heaviest  rainfall  for  this  section  was  48.67  inches  in  1876  and  the 
next,  48.11,  in  1881.  About  18.8  per  cent  of  the  total  rainfall  occurs  in 
winter;  29.7  per  cent  in  spring;  28.9  per  cent  in  summer,  and  22.6  percent 
in  autumn.  May  and  June  have  the  heaviest  rainfall,  4.26  inches,  and 
4.22  inches.  October  has  the  least  rainfall,  2.04  inches,  while  December, 
January,  and  February  have,  respectively,  2.24,  2.27,  and  2.28  inches. 
In  this  section  about  one-fifth  of  the  Aprils,  Mays,  and  Junes  are  dry, 
and  about  two-fifths  of  the  Julys  and  Augusts. 

SOUTHERN  DISTRICT. — The  southern  district  has  the  greatest  rainfall 
of  any  part  of  the  state,  the  average  for  the  past  thirty-one  years  being 


62  BULLETIN  No.  86.  [June, 

42.19  inches,  with  seventeen  years  below  normal.  The  least  rainfall  was 
30.05  inches  in  1872  and  the  next,  30.34  inches,  in  1901.  The  greatest 
rainfall  was  55.68  inches  in  1882  and  the  -next  54.03  inches  in  1876. 
About  21.6  per  cent  of  the  rain  falls  in  December,  January,  and 
February,  30.6  per  cent  in  March,  April,  'and  May,  26  per  cent  in  June, 
July,  and  August,  and  21.8  per  cent  in  the  autumn  months.  March  is 
the  wettest  month  with  an  average  of  4.42  inches.  June  is  next  with  4.29 
inches.  October  has  the  least  rainfall,  2.25  inches.  Nearly  one-sixth 
of  the  months  of  April,  May,  and  June  have  less  than  two  inches  of  rain, 
while  about  one-fifth  of  the  months  of  July  and  August  are  dry.  The 
nature  of  the  soil  in  this  part  of  the  state  is  such  that  a  short  drouth  or  a 
heavy  rainfall  produces  more  injurious  effects  upon  the  growth  of  cereal 
crops  than  in  the  central  and  northern  parts  of  the  state. 

ENTIRE  STATE. — The  average  rainfall  for  the  state  is  37.39  inches. 
The  least  was  25  inches  in  1901,  the  next  being  28.33  inches  in  1894. 
The  greatest  rainfall  was  in  1898,  47.39  inches,  and  the  next  was  45.47 
inches  in  1876;  1882  and  1883  had  about  45  inches  each.  The  six  most 
northern  counties  show  an  average  of  11.3  inches  less  than  the  seven  most 
southern  counties. 

A  peculiarity  in  the  distribution  of  the  rainfall  in  the  southern  part 
of  the  state  is  due  to  the  topography  of  that  region.  The  Ozark  Ridge, 
spoken  of  before,  extends  across  the  northern  parts  of  Union,  Johnson, 
Pope,  and  Hardin  counties  with  an  average  altitude  of  about  800  feet. 
This  ridge  causes  a  much  heavier  rainfall  in  these  counties,  amounting 
to  7.15  inches  more  annually  than  in  the  counties  immediately  north 
of  the  ridge.  This  difference  is,  of  course,  due  to  the  greater  condensa- 
tion of  the  moisture  as  the  south  winds  pass  over  this  higher  region. 
Another  rainy  region  occurs  along  the  Wabash  river  extending  north 
into  Crawford  County,  giving  to  the  counties  along  the  river  about  three 
inches  more  rainfall  than  to  those  in  the  next  tier  west. 

This  is  probably  due  to  the  break  in  the  Ozark  Ridge,  through  which 
the  Ohio  River  passes.  The  moisture  is  carried  through  this  gap  without 
condensation,  and  is  then  rather  uniformly  distributed  to  the  north. 
It  shows  what  the  condition  of  southern  Illinois  would  be  without  the 
Ozark  Ridge.  A  corresponding  increase  of  rainfall,  but  not  so  noticeable, 
is  found  along  the  Mississippi  River  as  far  north  as  Madison  County. 


1903.] 


CLIMATE  OF  ILLINOIS. 


63 


TABLE  5. — AVERAGE  TEMPERATURE,  MONTHLY  AND  ANNUAL. 
DEGREES  FAHRENHEIT. 


Counties.  —  Northern  District. 

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1 

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s 

i 

& 

S 

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1 

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18.4 

23.3 
20.4 
23.6 
20.2 
20.8 
?4  <1 

20.8 

21.7 
20.4 
24.8 
21.9 
•21.  6 
74   1 

30.8 
35.3 
32.5 
34.0 
32.4 
33.4 
36.9 

46.6 
51.1 
48.4 
44.2 
47.9 
48.4 
50.5 
49.7 
51.5 
51.0 
49.1 
49.0 
48.5 
48.7 
47.4 
50.9 
45.8 
50.7 

55.7 
62.4 
59.8 
54.6 
58.8 
59.2 
62.0 
61.6 
62.6 
62.3 
60.2 
60.6 
59.5 
60.4 
57.4 
62.4 
55.7 
61  f. 

67.0 
72.2 
68.9 
66.9 
68.9 
69.2 
71.6 
70.9 
71.3 
71.1 
70.5 
69.0 
69.8 
70.1 
69.2 
70.9 
65.1 
71  7 

72.1 
76.0 
73.6 
72.5 
72.6 
73.6 
76.9 
75.4 
75.5 
75.3 
74.8 
77.1 
74.2 
73.3 
72.4 
75.1 
70.5 
75  7 

69.8 
73.5 
70.7 
71.1 
69.7 
71.8 
73.6 
72.6 
73.2 
73.8 
71.6 
71.8 
71.9 
71.3 
69.4 
73.1 
69.5 
7?  5 

61.7 

65.7 
62.8 
63.3 
63.0 
63.4 
65.3 
64.3 
65.5 
65.6 
64.3 
63.4 
66.3 
65.0 
63.8 
67.0 
62.7 
65.5 

49  4 

54.7 
50.6 
52.8 
50.2 
151.0 
54.0 
53.0 
54.2 
53.9 
53.4 
52.1 
,52A 
50.6 
48.0 
53.8 
49.9 
53.8 

33.9 
38.1 
3.5.2 
38.5 
34.6 
36.2 
40.1 
39.4 
38.4 
37.0 
39.7 
35.4 
36.3 
35  7 
34.4 
39.0 
35.8 
38.9 

22.0 
25.7 
2.5.2 
28.1 
28.2 
26.4 
29.5 
30.2 
31.5 
26.8 
29.1 
34.4 
25.8 
30.4 
27.4 
24.3 
29.0 
29.0 

45.7 
50.0 
47.4 
47.9 
47.4 
47.9 
50.8 
50.0 
50.5 
49.6 
49.7 
48.9 
48.4 
48.8 
47.6 
49.8 
46.9 
50.3 
48  4 
50.6 
45.7 
51.0 
49.4 
48.2 
50.8 
49.4 
48.9 
49.4 
47.0 
50.5 
47.8 
49.7 
47  0 
51.8 

Carroll  

Cook  
DeKalb   

DuPage  .               

Ford                                          •    • 

Grundy  

24.0 
23.3 
22.3 
24.8 
19.2 
20.3 
22.4 
19.7 
24.5 
23.5 
23.4 

23.2 
22.1 
20.9 
23  1 
21.5 
22.5 
22.9 
22.1 
21.4 
23.1 
?4  9 

35.6 
36.6 
35.5 
36.0 
33.4 
33.6 
35.5 
40.0 
35.5 
32.2 
35  9 

Henderson  

Henry  

Kane   

Kankakee   

Kendall  .                      

Knox  

Lake  

LaSallc          

22.3ll9.6l33.8 

48.8 
49.9 
46.3 
52.4 
48.1 
49.7 
53.4 
50.9 
45.2 
50.9 
47.0 
51.5 
49.3 
50.0 

60.8 
60.6 
57.9 
62.0 
61.4 
60.3 
63.6 
59.6 
61.0 
61.8 
58.5 
62.6 
60.5 
61.8 

69.9 
70.5 
66.4 
71.4 
70.8 
68.0 
74.3 
70.9 
70.5 
71.0 
69.0 
71.3 
69.9 
71.0 
69.0 
73.1 

74.6 
75.8 
71.8 
76.5 
75.4 
74.3 
78.3 
74.1 
75.3 
75.2 
73.3 
75.5 
74.1 
74.8 
73.3 
77.8 

72.5 
72.7 
69.5 
73.3 
73.0 
72.5 
74.8 
72.4 
72.6 
72.8 
70.9 
73.2 
71.5 
72.4 
70.9 
74.8 

64.4152.6 
65.451.9 
61.748.3 
65.053.3 
65.1  53.5 
64.252.8 
67.354.4 
64.650.7 
64.653.3 
66.053.8 
63.050.7 
65.5  54.2 
63.051.2 
64.552  9 
63.050.7 
66.854.4 

36.6 
39.3 
33.7 
40.1 
37.9 
37.1 
39.8 
35.4 
37.7 
35.9 
35.3 
38.4 
35.4 
39.4 
35  .  3 
39.8 

24.7 
30.6 
23.4 
32.1 
28.4 
24.8 
30.7 
30.1 
27.2 
25.8 
25.5 
31.5 
24.9 
27.4 
25.5 
29.9 

Livingston  

25.4 
18.5 
26.6 
21.8 
21.0 
24.6 
21.6 
21.7 
22.7 
19.1 
23.3 
19  4 
?3  ? 

25.0 
19.7 
23.5 
22.5 
19.9 
27.3 
25.8 
23.1 
20.6 
20.3 
22.1 
20.9 
?3  1 

35.1 
30.8 
35.8 
35.4 
34.2 
38.7 
35.1 
35.0 
35.8 
31.8 
36.6 
32  9 
35.5 

McHenry  '  

Mercer  
Ogle       

Peoria  

Putnam  .  .  . 

Stark  

Stephenson  
Warren  
Whiteside  

Will 

Winnebago  

19.1 
24.6 

20.3 
26.1 

31.8 
38.0 

47.0 
52.8 

58.5 
63.6 

Woodford  '      ...            

Counties.  —  Central  District. 

9 

>-> 

f 

(z* 

1 

£ 

•< 

h 

oS 

S 

I 

>-> 

72.5 
73.4 
74.7 
73.4 
71.8 
72.8 
73.0 
72.9 
73.6 
73.0 
72.8 
73.1 
73.4 
75.2 
74.8 
73.2 
73.5 
72.4 
73.6 
74.7 
72.2 
73.3 
74.0 
75.2 
72.4 
74.2 
73.0 
74.1 
73.7 
69.7 
69.9 
73.4 
72.0 
74.1 
73.7 
72.7 
74.0 
72.4 

j*. 

1-9 

77.2 
76.5 
77.8 
76.5 
75.6 
76.7 
76.6 
77.2 
77.1 
76.6 
76.5 
76.0 
77.4 
77.5 
77.7 
76.8 
76.7 
78.6 
77.1 
77.8 
75.2 
76.3 
76.9 
77.1 
76.6 
77.5 
76.8 
77.6 
77.8 
74.1 
74.1 
76.7 
76.4 
76.0 
77.8 
77.0 
76.5 
75.7 

ti 
3 

75.3 
74.5 
75.5 
74.5 
73.0 
74.9 
74.7 
74.7 
74.9 
74.7 
74.1 
74.5 
75.0 
76.0 
75.6 
75.6 
74.3 
74.6 
74  9 
75.5 
73.5 
75.0 
76.3 
76.3 
73.1 
75.9 
74.4 
76.9 
76.9! 
71.5; 
71.4 
75.2 
73.9 
74.0 
76.9 
74.8 
73.9 
73,4 

•fc 

& 

67.1 
67.1 
69.1 
67.1 
65.6 
67.8 
67.5 
67.9 
66.9 
67.5 
67.8 
67.1 
67.9 
71.2 
69.5 
67.2 
67.2 
66.7 
66.9 
69.1 
66.8 
67.9 
69.6 
67.4 
67.6 
69.0 
67.5 
69.4 
67.9 
66.1 
65.3 
68.1 
fifl.8 
65.2 
67.9 
67.3 
68.0 
66.2 

o 

O 

o 
fc 

4^1 

Adams  

28.2 
27.5 
31.0 
27.5 
25.5 
28.2 
29.6 
28.4 
30.2 
29.6 
26.3 
27.9 
27.6 
29.8 
29.4 
26.3 
27.0 
24.7 
30.2 
31.0 
27.7 
27.5 
29.7 
25.4 
25.0 
27.8 
26.8 
30.8 
29.0 
25.3 
25.2 
28.2 
26.4 
26.7 
29.0 
25.8 
27.0 
26  4 

25.9 
27.0 
30.9 
27.0 
25.9 
28.7 
30.5 
30.2 
30.4 
30.5 
25.2 
24.8 
27.7 
27.7 
28.9 
22.5 
29.4 
24.0 
30.4 
30.9 
27.3 
25.6 
28.9 
23.3 
24  8 
27.7 
27.7 
28.2 
26.6 
24.4 
24.0 
26.8 
29.4 
26.4 
26.6 
29.2 
28.5 
26.9 

38.5 
37.5 
41.5 
37.5 
37.6 
38.3 
40.4 
40.0 
42.6 
40.4 
39.1 
39.2 
38.1 
42.1 
41.5 
37.8 
39  .  0 
37.5 
42.  G 
41.5 
38.7 
40.2 
41.2 
38.6 
38.0 
39.9 
39.5 
41.3 
39.9 
37.1 
36.3 
39.8 
39.2 
38.5 
39.9 
38.9 
39.4 
38.6 

52.3 
54.1 
55.1 
54.1 
51.2 
53.3 
54.2 
53.6 
54.1 
54.2 
52.6 
52.5 
52.0 
55.7 
55.4 
52.8 
55.4 
52.5 
54.1 
55.1 
52.7 
53.3 
54.6 
53.3 
52.0 
53.4 
53.4 
54.6 
52.7 
50.5 
50  .  ?. 
54.3 
53.4 
53.8 
52.7 
53.5 
53.3 
51.7 

64.4 
63.9 
64.5 
63.9 
61.6 
63.5 
64.4 
63.5 
64.0 
64.4 
63.7 
63.1 
63.4 
64.5 
65.8 
64.1 
63.3 
59.9 
64.0 
64.5 
62.2 
64.0 
64.3 
64.2 
63.3 
63.8 
63.3 
67.6 
64.6 
61.9 
61.2 
64.1 
63.1 
63.6 
64.6 
63.8 
63.1 
62.2 

56.3 
55.8 
57.2 
55.8 
53.3 
55.4 
55.6 
55.7 
55.2 
55.6 
56.5 
55.2 
54.7 
58.5 
56.9 
56.4 
54.7 
55.0 
55.2 
57.2 
55.8 
56.7 
57.6 
56.4 
56.4 
57.8 
57.0 
58.2 
58.5 
53.2 
53.0 
56.9 
56.7 
55.5 
58.5 
54.5 
56.4 
54,0 

41.528.852.3 
39.531.862.4 
43.433.454.5 
39.531.852.4 
39.730.4:50.9 
42.432.8!52.9 
41.537.453.8 
42.5,32.653.3 
42.833.353.8 
41.537.4153.8 
40.6  29.7  52.1 
41.1  30.452.1 
41.930.652.5 
42.733.054.5 
42.633.254.3 
39.928.851.8 
41.2  33.3  53.0 
39.226.450.9 
42.833.353.8 
43.433.454.5 
40.831.952.1 
41.230.552.6 
42.232.354.0 
39.0)29.252.1 
40.0128.951.5 
40.831.553.3 
41.031.852.7 
43.831.5,54.5 
43.0  29.753.3 
39.928.650.2 
38.328.451.3 
40.431.452.9 
41.4  32.0  52.5 
39.431.952.1 
43.029.753.3 
41.533.252.6 
40.1  31.752.6 
39.730.251.4 

Brown  

Calhoun  

Cass     .          .    .                    ... 

Champaign   
Christian  ,  .  .  . 

Clark  
Coles  .   

Crawford                                  .  . 

Cumberland  ...    .        

DeWitt  

Douglas  

Edgar  
Effingham       .                     ... 

Fayette  .        .    .              

Fulton  

Greene  

Hancock. 

Jersey  

Logan  

Macon  . 

Macoupin  .  . 

McDonough 

McLean  

Mason  . 

Menard  
Montgomery  

Morgan  ...        . 

Moultrie  
Piatt  .  . 

Pike  

Sangamon  .    . 

Schuyler  

Scott  .... 

Shelby  
Tazewell  

Vermilion  .  . 

64 


BULLETIN  No.  86. 


[June, 


TABLE  5. — AVERAGE  TEMPERATURE,  MONTHLY  AND  ANNUAL. 
DEGREES  FAHRENHEIT. — Continued. 


Counties.  —  Southern  District. 

c 
3 

4 

— 

| 

1 

5 

S 

o 
a 

1 

>> 

i 

M 
< 

I 

"5 
O 

i 

* 

0 
<0 

Q 

i* 
3g 

Alexander  

35.4 
29.2 
29.9 
30  5 
32.3 

38.4 
29.8 
32.3 
30.0 
30  1 

46.8 
41.0 
40.8 
41.7 
43.5 

55.2 
55.2 
55.1 
54.9 
55.7 

65.4 
66.5 
63.6 
66.4 
66.4 

75.6 
74.5 
73.2 
74.5 
75.1 

79.1 

77.7 
76.4 

77.8 
78.4 

74.2 
75.5 
74.3 
75.9 
76.8 

70.6 
68.4 
67.7 
68.9 
69  3 

58.9 
56.0 
54.9 

50  .  8 
57  2 

46.7 
42.5 
42.9 
42.9 
44  5 

39.4 
33.9 
35.5 
33.9 
33  9 

57.1 
54.2 
53.9 
54.5 
55.3 

Bond  

Clay     .      . 

Clinton  

Edwards  . 

Franklin  

33.3 
34.6 
32.5 
35.5 
32.7 
32  9 

33.5 
33.5 
34.3 
34.0 
33.3 
30.6 
33.2 
30.8 
31.1 
32.6 
35  9 

44.7 
44.7 
42.9 
45.5 
45.8 
43.1 
46.3 
40.7 
41.1 
41.6 
49  0 

56.6 
56.1 
56.0 
57.3 
58.1 
54.4 
57.8 
55.3 
55.3 
56.3 
59.1 

66.7 
66.5 
64.9 
67.2 
68.4 
66.3 
68.6 
65.8 
65.4 
64.8 
69  9 

75.6 
76.0 
74.8 
76.3 
77.5 
75.2 
76.4 
75.5 
73.4 
75.3 
78.5 

78.8 
78.9 
78.2 
79.7 
79.2 
78.2 
79.9 
78.4 
77.4 
77.7 
81  6 

77.2 
77.9 
75.9 
79.7 
78.7 
76.9 
79.2 
75.6 
74.8 
73.2 
80  8 

69.5 
71.2 
69.1 
66.4 
70.2 
69.9 
72.5 
69.7 
68.4 
66.9 
74.0 

57.3 
57.6 
56.7 
59.2 
58.0 
58.6 
60.0 
56.8 
55.7 
55.2 
62.0 

45.1 
46.6 
44.7 
47.2 
44.1 
43.2 
48.1 
43.7 
42.5 
41.4 
48.1 

36.4 
35.9 
37.1 
38.1 
36.5 
33.5 
36.4 
35.3 
34.6 
36.3 
39  2 

56.2 
56.6 
55.6 
57.2 
56.9 
55.2 
57.9 
54.9 
54.0 
54.4 
59.6 

Gallat  in  

Hamilton  

Hardin  

Jackson  

.  Johnson  

36.0 
31.4 
28.3 
31.3 
37  4 

Lawrence  

Madison  

Marion  

Massac. 

MOP  roe  .  .    . 

32.4 
32.9 
35.3 
35  4 

32.8 
31.4 
35.2 
38.4 
32.8 
32.1 
33.2 
33.5 
33.0 
31.9 
31.2 
30.1 
34.2 
31.5 

43.5 
44.1 
42.2 
46.8 
43.5 
42.6 
43.3 
44.7 
45.0 
43.2 
43.2 
43.5 
44.2 
45.9 

56.3 
55.4 
58.1 
55.2 
56.3 
54.9 
56.5 
56.1 
56.8 
55.0 
54.8 
55.5 
56.6 
53.1 

65.5 
67.2 
67.0 
65.4 
65.5 
65.3 
65.8 
66.5 
67.4 
65.2 
65.4 
66.3 
66.6 
68.7 

74.1 
75.8 
76.2 
75.6 
74.1 
75.3 
75.4 
76.0 
75.1 
74.9 
73.5 
74.7 
76.6 
72.3 

77.4 
78.2 
79.4 
79.1 
77.4 
78.1 
79  0 
78.9 
79.0 
77.9 
77.1 
77.9 
79.0 
80.0 

75.7 
77.9 
78.0 
71.0 
75.7 
75.8 
78.7 
77.9 
77.9 
76.6 
76.1 
76.7 
77.8 
79.3 

69.3 
71.1 
71.5 
70.6 
69.3 
69.0 
69.8 
71  2 
71.6 
68.9 
69.3 
69.5 
71.7 
72.0 

59.5 
59.3 
62.5 
58.9 
59.5 
56.0 
57.1 
57.6 
61.0 
56.5 
57.3 
57.9 
57.9 
60.9 

44.4 
46.2 
47.0 
46.7 
44.4 
43.4 
43.1 
46.6 
47.5 
44.4 
43.3 
45.1 
45.0 
48.4 

34.6 
33.3 
38.9 
39.4 
34.6 
35.6 
34.9 
35.9 
35.1 
34.1 
35.6 
33.8 
36.3 
35.8 

55.4 
56.1 
57.6 
56.9 
55.4 
54.9 
55.6 
56.6 
56.8 
55.1 
54.9 
55.3 
56.7 
56.9 

Perry  ... 

Pope  

Pulaski  

Randolph  ....                     .  .  .  . 

32.4 
31.4 
30.9 
34.6 
32.2 
32.6 
32.0 
32.9 
34.6 
35.8 

Richland  .  . 

St.  Clair  

Saline  

Union  

Wabash  
Washington  
Wayne.  .  . 

White  

Williamson 

TABLE  6.— AVERAGE  MONTHLY  TEMPERATURE. 


i 

1-3 

j 
a 

s 

a 

a 

M 

a 
•4 

1 

1 

>f 
i-» 

M 
^ 

1 

CO 

to 

O 

i 

& 

o 

V 

o 

&s 

$« 

Northern  District  
Central  District  
Southern  District  

22.1 
27.8 
32.9 

22.7 
27.4 
32.8 

34.7 
39.4 
43.8 

49.5 
53.4 
56.0 

60.3 
63.7 
66.4 

70.0 
73.2 
75.2 

74.6 
76.7 
78.5 

76.6 

72.1 
74.7 
76.6 

74.4 

64.5 
67.6 
69.9 

50.7 
56.0 
58.4 

37.2 
41.2 
44.7 

27.8 
31.5 
35.8 

48  9 
52.7 
55.9 

Average  for  state  

27.4 

27.3 

39.2 

52.8 

63.3 

72.7 

67.1 

55.0 

41.0 

31.5 

52.3 

TEMPERATURE. 

The  state  is  subject  to  varying  extremes  of  temperature  in  short 
periods  of  time,  due  to  the  passage  of  cyclones,  as  has  been  already 
explained.  The  average  temperature  for  the  state  is  52.3°  Fahrenheit. 
There  is  a  gradually  increasing  temperature  from  46.9°  in  the  northern 
tier  of  counties  to  57.6°.  in  the  southern,  or  a  difference  of  10.7°.  The 
three  summer  months  for  the  northern  counties  compared  with  the  most 
southern  ones  are  about  7°  cooler,  while  the  winter  months  are  about 
17.2°  cooler.  The  temperature  is  more  uniform  in  the  southern  part,  as 
may  be  seen  by  comparing  the  average  monthly  temperatures  for  the 
northern  and  southern  districts.  The  differences  between  the  January 
temperatures  of  the  two  districts  is  10.8°,  while  for  July  it  is  only  3.9°. 
The  average  summer  temperature  for  the  northern  district  is  48°  higher 
than  the  winter,  while  in  the  southern  part  the  summer  is  44.4°  higher 
than  the  winter. 


1903.]  CLIMATE  OF  ILLINOIS.  v        65 

NORTHERN  DISTRICT. — The  average  temperature  for  this  district  is 
48.9°.  The  coldest  month  is  January,  with  an  average  of  22.1°,  while 
February  has  22.7°.  July  has  the  highest  average  temperature,  74.6°,  or 
52.5°  above  January.  Boone  and  McHenry  counties  have  the  lowest 
monthly  average,  18.4°  and  18.5°.  The  lowest  recorded  temperature  was 
at  Riley  near  Marengo  in  McHenry  County,  31°  below  zero,  in  January, 
1884,  and  at  the  same  place,  nineteen  winters  have  had  temperature  of 
20°  or  more  below  zero  since  1870,  and  during  every  winter  since  that  time 
the  temperature  has  been  at  least  10°  below  zero.  The  average  of  the 
lowest  temperatures  observed  at  the  different  stations  in  1884  was  25.6° 
below  zero,  and  1898  is  the  only  year  in  which  the  average  of  the  lowest 
temperatures  was  higher  than  10°  below  zero  since  1872.  The  year  1875 
shows  the  lowest  annual  temperature,  43.9°,  or  5°  below  normal.  The 
extreme  range  of  'temperature  for  this  section  is  143°.  The  average 
annual  range  is  about  115°,  varying  from  100°  to  128°.  The  seasonal 
range  of  temperature  varies  with  the  season,  the  average  being  about  75° 
for  winter  and  53°  for  summer,  the  spring  and  fall  months  varying  between 
these.  The  highest  temperature  recorded  was  at  Ottawa,  112°  in  1901, 
and  this  summer  was  the  hottest  shown  by  the  records,  not  only  of  this 
section,  but  of  the  central  and  southern  sections. 

CENTRAL  DISTRICT. — The  records  in  this  part  of  the  state  are  not  as 
complete  as  for  the  northern  part,  very  few  extending  as  far  back  as 
1882.  The  average  temperature  for  this  district  is  52.7°. -  The  extreme 
range  of  temperature  is  139°.  The  average  annual  range  is  about  109°, 
varying  from  95°  to  130°.  The  seasonal  range  is  greater  during  winter, 
being  about  75°,  varying  from  60°  to  92°,  while  for  summer,  the  average 
range  is  about  50°,  with  a  variation  of  from  40°  to  68°.  The  coldest 
month  is  February,  27.4°,  with  January  27.8°,  while  the  average  for  Decem- 
ber is  31.5°,  or  one-half  degree  below  freezing.  The  lowest  temperature 
recorded  in  this  region  was  in  January,  1884,  28°  below  zero,  and  the 
highest  was  112°  in  1901.  The  average  of  the  lowest  temperatures  for 
this  district  was  24.7°  below  zero  in  1884,  which  was  only  about  1°  above' 
the  same  average  for  the  northern  district.  At  Springfield,  since  1880, 
only  three  winters  show  a  temperature  of  20°  or  more  below  zero,  and 
thirteen  show  10°  or  more  below. 

SOUTHERN  DISTRICT. — The  records  for  this  district,  with  the  exception 
of  Cairo  and  St.  Louis,  extend  no  further  back  than  1887.  The  average 
temperature  is  55.9°.  January  and  February  have  almost  the  same 
average  temperature,  32.9°  and  32.8°.  No  month  in  this  section  shows 
.  an  average  temperature  below  freezing.  The  lowest  temperature  ob- 
served was  in  February,  1899,  23°  below  zero  in  Randolph  County,  while 
the  average  lowest  temperature  for  this  year  was  18.7°  below.  The 
highest  temperature  recorded  was  in  Marion  County,  115°  in  July,  1901, 
and  at  several  places  112°  and  113°  were  observed.  The  extreme  range 


66 


BULLETIN  No.  86. 


[June, 


of  temperature  is  138°,  and  an  annual  range  of  128°  has  been  known, 
although  the  average  is  about  103°.  The  winter  range  of  temperature  is 
about  75°,  varying  from  50°  to  90°,  while  the  summer  range  is  about  48°, 
with  variations  from  32°  to  67°. 

FROST. 

Data  for  the  time  of  the  last  killing  frost  in  spring  and  the  first 
in  autumn  have  been  collected  and  the  average  time  of  frost  for  each 
district  has  been  found  and  is  shown  in  the  accompanying  table. 


Districts. 

Northern 
Central 
Southern    . 


Average  date  for 

last  killing 
frost  in  spring. 
April  29 
April  21 
April  14 


Average  date  for 

first  killing 
frost  in  autumn. 

October  6 

October  10 

October  18 


Days 

between 

killing  frosts. 

160 

172 

187 


From  the  table  we  see  that  the  season  without  injurious  frosts  is 
nearly,  two  weeks  longer  in  the  central  and  four  weeks  in  the  southern 
than  in  the  northern  section.  The  average  length  of  time  between 
killing  frosts  in  the  northern  tier  of  counties  is  155  days,  while  that  of 
the  seven  southern  counties  is  195,  or  40  days  longer.  Springfield  gives 
173  days  between  frosts,  the  average  for  spring  and  fall  frosts  being 
April  24th  and  October  14th.  This  is  about  the  average  for  the  central 
section. 


TABLE  7. — PERCENT  OF  TIME  DURING  WHICH  THE  WIND   BLOWS  FROM  THE 
DIRECTION  INDICATED. 


Districts. 

December    January,  and  February. 

March,  April,  and  May. 

fc 

£ 
VT 

& 

£ 
02 

02 

B 
ad 

B 

B 
fc 

fe 

& 
fc 

* 

9.3 
6.4 
4.4 

£ 

02 

03 

B 

02 

B 

B 

^ 

17.4 
9.9 
6.0 

Northern  
Central  
Southern  

2.4 
1.7 
15.3 

45.    27.8 
63.2    9.1 
37.11  7.8 

16.2 
12.3 
9.8 

4.5 
8.3 
24  4 

1.5 
4.4 
3.1 

.3 
.2 

.8 

1.8 
.8 
1.6 

6.7 
6.4 
11.3 

23.7 
27.4 
16.4 

10.5 
15.5 
16.3 

11.6 
14.5 
32.8 

7.1 
15.6 
11.3 

7.6 
4.3 
1.5 

Districts. 

June,  July,  and  August. 

September,  October,  and  November. 

fc 

£ 

fc 

£ 

& 
to 

OQ 

B 
ad 

B 

B 

fc 

K 

£ 

fc 

H 

£ 

00 

02 

» 
OQ 

B 

B 
fc 

4.1 
2.1 
3.2 

Northern  
Central  
Southern  

3.8 
3.0 
5.4 

10.1 
4.5 
.8 

5.135.5  15.3 
1.443.521.7 
1.834.440.6 

8.0 
10.7 
6.7 

8.5  13.5 
3.012.0 
2.2    8.1 

3.1  19.2 
2.819.6 
8.4  13.9 

10.5 
4.2 
3.0 

28.624.5 
27.626.3 
17.242.3 

8.2    1.6 
16.8       .7 
11.3       .7 

YEARLY  SUMMARY. 


Districts. 

* 

£ 
fc 

•^ 

£ 

02 

02 

B 

02 

B 

B 
fc 

Northern  

4.1 

23  9 

12  8 

24  3 

14  3 

6  2 

4.7 

9  4 

Central  .    .  .    .          ... 

3   S 

27.8 

5  0 

24.4 

17.9 

12.9 

2  1 

6  3 

Southern  .. 

10  1 

16  8 

4  2 

19  4 

35  ?. 

8   1 

1   4 

4  8 

1903.]  CLIMATE  OF  ILLINOIS.  67 

TABLE  8. — AVERAGE  HOURLY  WIND  VELOCITY  IN  MILES. 


Stations. 

a 
I 

j=> 
j* 

&H 

C 

03 
S 

a 
•< 

i 

§ 

1 

1-5 

>> 

3 

>-5 

bb 

«< 

*a 

a. 

$ 

•*j 

o 

O 

g 

fe 

u 

a> 
Q 

fe'SP 

4» 

Chicago  

13  ft 

14  3 

14  8 

14  3 

13  0 

11    0 

10  9 

10  6 

12  4 

13  0 

13  9 

13  9 

12  97 

Davenport  .... 

8  ,ft 

9  ? 

10  3 

10  6 

9  0 

7  4 

6  4 

6  0 

7  ft 

7  9 

8  7 

8  ft 

8  33 

Dubuque  

ft  8 

6  1 

7  ? 

7  ?! 

6  ? 

,ft  4 

4  7 

4  4 

5  2 

ft  6 

6  0 

ft  6 

5  8 

Hannibal  

9  6 

10  0 

11   fi 

11  0 

9  5 

8  1 

7  .ft 

6  8 

8  2 

8  7 

9  8 

9  7 

9  2 

Keokuk  

7  8 

8  ?, 

9  4 

9  0 

7  ft 

6  ft 

ft  9 

ft  4 

6  4 

7  0 

8  0 

8  0 

7  4 

Springfield  .  . 

10  1 

10  7 

11    3 

10  6 

8  7 

7  4 

6  7 

6  ft 

7  9 

8  8 

10  0 

10  1 

9.1 

Cairo   

8  6 

9  3 

10  5 

9  4 

7  6 

fi  ft 

ft  ft 

ft  3 

6  0 

6  4 

8  4 

8  7 

7  7 

St.  Louis.  .  . 

11   ?, 

11   4 

]?,  1 

11    3 

9  9 

8  9 

8  ? 

8  1 

8  fi 

9  7 

11    1 

11    1 

10.1 

WIND. 

DIRECTION  AND  VELOCITY. — The  state  lies  in  the  belt  of  prevailing 
westerly  winds  in  which  the  general  atmospheric  movement  is  from  west  to 
east,  yet  the  presence  of  the  cyclones  of  this  belt  causes  great  variations, 
both  in  the  direction  and  velocity-  of  the  wind.  The  wind  direction  has 
been  determined  for  seasons  and  not  for  months.  The  velocity  is  given 
in  miles  per  hour  and  was  obtained  from  the  published  records  of  the 
weather  bureau  stations  within  the  state  and  the  five  along  the  Missis- 
sippi River.  The  velocity  was  determined  by  the  anemometer,  but 
comparisons  are  very  difficult,  because  of  the  varying  heights  of  the 
instruments  above  the  ground.  At  Chicago  the  anemometer  is  274  feet 
above  the  ground,  at  St.  Louis  210,  and  at  other  stations  as  low  as  79 
feet.  As  a  consequence,  Chicago  shows  the  highest  wind  velocity  and  St. 
Louis  next.  The  velocities  given  are  taken  from  Davenport,  Iowa,  for  the 
northern  district,  Springfield  for  the  central,  and  Cairo  for  the  southern. 
.  The  velocity  of  the  wind  is  greater  during  the  cooler  months  of  the 
year,  February,  March,  and  April  being  the  windiest  months,  while  July, 
August,  and  September  have  the  least  atmospheric  movement.  The 
season  of  this  increased  velocity  is  very  significant  to  the  agriculturist, 
increasing,  as  it  does,  the  amount  of  evaporation.  In  some  cases  the 
soil  may  need  to  be  dried  and  then  it  is  a  benefit. 

The  direction  of  the  wind  for  the  northern  section  is  southerly  for 
45  percent  of  the  time,  while  it  blows  from  a  north,  northwest,  and 
west  direction  41  percent  of  the  time,  giving  a  prevailing  southerly 
wind.  In  the  central  region  the  southerly  wind  blows  for  55  percent  of 
the  time  while  the  colder  winds  from  the  north,  northwest,  and  west 
blow  about  36  percent  of  the  time.  In  the  southern  section  the  colder 
winds  blow  for  31  percent,  while  the  southerly  winds  blow  for  62  percent 
of  the  time. 

1.  WINTER  MONTHS. — During  these  months  the  northwest  wind  is 
the  most  frequent  in  all  sections  of  the  state,  blowing  for  45  percent  of 
the  time  in  the  northern,  60  percent  in  the  central,  and  37  percent  in  the 
southern  district.  In  the  northern  section  the  west  is  next  in  frequency 


68  BULLETIN  No.  86.  [June, 

to  the  northwest,  while  in  the  central  the  southwest  wind,  and  in  the 
southern,  the  south  wind  are  next  in  frequency.  The  east  and  northeast 
winds  are  unimportant.  The  velocity  of  the  winds  is  quite  high, 
being  8.7  miles  an  hour  for  the  northern,  10.3  miles  for  the  central, 
exceeding  slightly  the  velocity  for  the  spring  months,  and  8.9  miles  for 
the  southern  section.  This  makes  the  winters  of  the  central  section 
slightly  more  disagreeable  than  those  of  the  other  sections. 

2.  SPRING  MONTHS. — During  this  period  the  northwest  wind  is  most 
frequent  in  the  northern  and  central  sections,  while  the  south  wind  blows 
for  about  one-third  of  the  time  in  the  southern  part.     The  northeast 
and  east  winds  assume  some  importance  during  these  and  the  summer 
months,  owing  probably  to  the  courses  of  the  low  areas  being  farther  south 
and  bringing  the  state,  and  especially  the  northern  and  central  parts  of 
the  state,  oftener  into  the  northern  part  of  cyclones  where  the  easterly 
winds  prevail.     The  southerly  winds  blow  for  about  35  percent  of  the 
time  in  the  northern  part,  45  percent  in  the  central,  and  about  60  per- 
cent in  the  southern.     The  velocity  of  the  wind  is  at  its  highest  during 
these  months,  the  average  in  the  northern  part  being  10  miles  an  hour,  in 
the  central  10.2    miles,  and  in  the  southern  9.2  miles.     April    has  the 
highest  velocity  in  the  northern  part,  and  March  in  the  central  and  south- 
ern, being  10.6  miles,  11.3  miles,  and  10.5  miles  for  the  different  sections. 
These  high  winds  are  apt  to  have  a  bad  effect  upon  the  unworked  soils 
rendering  them  cloddy,  especially  during  the  frequent  dry  spells  of  spring. 

3.  SUMMER  MONTHS. — During  this  time  the  southwest   forms  the 
most  frequent  wind  in  the  northern  section,  occurring  35^  percent  of  the 
time,  and  also  for  the  central  part,  occurring  43^  percent  of  the  time. 
In  the  southern  part  the  south  wind  is  prevalent  for  40J  percent  of  the 
time  with  the  southwest  34  percent.     In  each  division  the  east  and  north- 
east winds  are  still  important.     The  southerly  winds  are  prevailing  ones 
during  these  months,  blowing  59   percent  of  the  time  in  the  northern 
district,  76  percent  in  the  central,  and  82  [percent   in   the   southern. 
The  velocity  of  the  wind  is  least  during  the  summer,  being  about  6.6  miles 
an  hour  in  the  northern  part,  6.9  miles  in  the  central,  and  5.8  miles  in 
the  southern.     August  shows  the  least  atmospheric  movement  of  any 
month  during  the  year. 

4.  AUTUMN  MONTHS. — The  northwest  wind  becomes  more  frequent 
during  this  time,  but  the  same  ones  are  predominant  as  in  summer.     The 
northeast  winds  have  become  less  frequent  until  they  blow  only  4  per- 
cent, 2  percent,  and  3  percent  in  the  north,  center,  and  south,  respec- 
tively.    The  southerly  winds  occur  for  61  per  cent  of  the  time  in  the 
northern  part,  71  per  cent  in  the  central,  and  70  per  cent  in  the  southern. 
The  velocity  of  the  wind  increases  during  this  time  until  it  becomes  8 
miles  for  the  northern,  8.9  miles  for  the  central,  and  7  miles  for  the 
southern  part. 


1903.] 


CLIMATE  OF  ILLINOIS. 


69 


TABLE  9. — DAYLIGHT  CLOUDINESS  IN  PERCENT. 
NORTHERN  DISTRICT. 


Station. 

c3 
Hj 

.0 
V 
ft 

i* 

a. 
<J 

ft 

s 

a5 
d 

>-> 

3 

»-s 

ti 

2 
< 

49 

OH 
<l> 

02 

-ij 
o 

0 

> 
o 
K 

6 

0 

a 

£i 

<<  * 

Chicago  

60 

57 

57 

50 

49 

46 

36 

4? 

43 

48 

59 

61 

51 

Davenport  .... 
Dubuque  

54 
51 

56 

54 

58 
55 

55 
53 

52 
52 

50 
50 

42 
41 

43 

42 

44 
45 

46 

48 

56 
54 

58 
59 

51 
52 

Average  

55 

56 

57 

53 

51 

49 

40 

4? 

44 

I  47 

56 

59 

51 

CENTRAL   DISTRICT. 


Hannibal  
Keokuk  

52 
47 

54 

48 

58 
53 

53 

49 

45 
45 

42 
43 

35 
35 

33 
33 

38 
36 

38 
36 

51 

46 

56 
51 

•46 
44 

Springfield  .... 

56 

57 

60 

56 

53 

54 

43 

40 

41 

41 

53 

60 

51 

Average  . 

52 

53 

57 

53' 

48 

46 

38 

35 

38 

38 

50 

56 

47 

SOUTHERN    DISTRICT. 


Cairo  

59 

59 

57 

54 

51 

5? 

45 

41 

4? 

40 

^5 

60 

51 

St.  Louis  

51 

54 

50 

48 

46 

41 

37 

38 

36 

36 

48 

47 

45 

Average  

55 

56.5 

53.5 

51 

43.5 

46.5 

41 

39.5 

39 

38 

51.5 

58.5 

48 

TABLE  10. — SHOWING  WHAT  PERCENT  THE  ACTUAL  SUNSHINE  is  OF  THE  POSSIBLE 
SUNSHINE  OF  THE  PLACE. 
CHICAGO. 


' 

a 
a 

•"9 

X> 
g 
A 

M 

03 

S 

E- 
<; 

>> 

03 
S 

o 

a 

1-5 

>> 

i-s 

bb 

< 

"a. 

£ 

-ij 

o 

O 

O  ' 

to 

d 
a> 

Q 

!& 

4> 

1894  

57 

57 

5? 

64 

62 

71 

85 

73 

70 

43 

37 

45 

60 

1895  .  . 

46 

67 

68 

68 

73 

83 

82 

79 

86 

77 

41 

28 

66 

1896  . 

35 

55 

65 

63 

78 

84 

66 

8? 

56 

63 

36 

28 

59 

1897  

38 

31 

50 

49 

62 

52 

59 

54 

71 

72 

32 

30 

50 

1898  

48 

44 

57 

54 

57 

50 

76 

63 

58 

26 

49 

51 

53 

1899  

49 

4?: 

32 

65 

61 

71 

66 

75 

54 

51 

38 

37 

53 

1900  . 

37 

47 

41 

61 

56 

63 

60 

60 

57 

66 

40 

38 

52 

1901  

40 

67 

36 

67 

50 

69 

77 

56 

67 

69 

52 

40 

58 

1902  . 

61 

58 

56 

67 

65 

58 

59 

67 

48 

67 

41 

33 

57 

Average  

46 

5? 

51 

6? 

62 

67 

70 

68 

63 

59 

44 

37 

56 

ST.  LOUIS. 


1894  .  .  . 

63 
74 
50 
48 
63 
49 
58 
51 

75 

69 
58 
46 
52 
71 
49 
51 

71 
72 
52 
65 
68 
64 
67 

66 
80 
74 
75 
68 
72 
70 
61 

91 
72 
71 
69 
80 
61 
78 
60 

82 
61 
72 
81 
75 
75 
.79 
75 

83 
76 
81 
81 
76 
80 
75 
52 

76 

82 
60 
90 

82 
65 
78 
57 

71 
79 
79 

88 
72 
67 
75 
69 

64 
51 
46 
52 
50 
58 
80 
38 

56 
48 
57 
29 
49 
51 
44 
38 

69 
64 
~64 
65 
64 
68 
57 

1895  

62 
48 
56 
50 
57 
64 
70 

1896  . 

1897  

1899  

1900  

1901  

1902  . 

Average  .  .  .  .1.  . 

58 

57 

59 

66 

71 

73 

75 

75 

74 

75 

55 

46 

65 

KEOKUK. 

1901  

56 

63 

70 
61 

36 

39 

54 
65 

62 
54 

63 
40 

73 

59 

75 
50 

67 
55 

65 

70 

69 

36 

38 
34 

61 
52 

1902  

SPRINGFIELD. 

1902  

59 

53 

47 

63 

62 

58 

76 

62 

53 

66 

42 

35 

56 

70  BULLETIN  No.  86.  [June, 

CLOUDINESS  AND  SUNSHINE. 

For  many  years  the  weather  bureau  has  been  collecting  data  that 
will  give  a  close  estimate  of  the  daylight  cloudiness.  Table  9  gives 
the  results  of  these  observations  expressed  in  per  cent.  November, 
December,  January,  February,  March,  and  April  are  the  cloudy  months  of 
the  year.  The  northern  part  is  cloudy  during  56  percent  of  the  day- 
light, the  central  and  southern  about  53  J  percent ;  or  in  other  words,  the 
northern  section  has  about  five  more  cloudy  days  than  the  other  sections 
during  the  months  named  above.  The  percent  of  cloudiness  is  much 
less  for  the  other  months  of  the  year,  the  northern  having  45J  percent, 
the  central  40^  percent,  and  the  southern  42  percent.  A  large  amount 
of  cloudiness  is  not  necessarily  accompanied  by  a  heavy  rainfall,  but 
cloudy,  and  consequently  cooler  weather  is  very  important  in  the  develop- 
ment of  some  crops.  December  is  the  cloudiest  month  of  the  year  for 
the  northern  and  southern  parts,  and  March  for  the  central,  although 
December  is  only  1  percent  less.  July  is  the  clearest  month  for  the  north- 
ern, August  for  the  central,  and  October  for  the  southern  part,  with  July 
and  August  only  1  percent  less.  Table  10  gives  the  percent  of  sunshine 
at  some  of  the  stations.  At  Chicago  the  sun  shines  56  percent  of  the 
time  that  it  is  possible  for  it  to  shine.  At  St.  Louis  the  average  sunshine 
is  about  65  percent.  At  Keokuk  and  Springfield  the  sunshine  recorders 
have  been' installed  but  a  short  time,  so  that  no  average  can  be  given  as 
yet.  It  is  interesting  to  compare  the  sunshine  records  for  1901 ,  a  very 
dry  year,  with  those  for  1902,  one  of  excessive  rainfall. 

GENERAL  SUMMARY. 

The  succession  of  weather  changes  is  due  almost  entirely  to  the  pas- 
sage of  cyclones  and  anticyclones,  or  lows  and  highs. 

The  approach  of  a  cyclone  is  usually  indicated  by  the  changing  of  the 
wind  to  a  southerly  or  an  easterly  direction  and  a  circle  around  the  sun 
or  moon. 

If  the  southern  part  of  a  cyclone  pass  over  a  place  the  wind  will 
at  first  be  from  the  southeast  or  south,  and  will  gradually  shift  around 
to  the  southwest,  west,  and  northwest  accompanied  by  a  lowering  of  tem- 
perature. The  rain  will  come  in  showers. 

If  the  center  of  the  cyclone  pass  over  a  place  there  will  be  a  sudden 
shifting  of  the  wind  from  a  southerly  to  a  northwest  direction  as  the 
center  of  the  storm  is  passed.  The  rainfall  may  be  either  showers  or 
steady  rain. 

If  the  north  part  of  the  storm  pass  over  a  place  the  wind  will  blow 
from  an  easterly  direction  and  will  shift  through  the  north  to  the  north- 
west, with  lowering  of  temperature.  The  rain  will  be  a  cold,  steady 
rain,  if  in  the  warmer  months,  and  snow,  if  in  winter. 


1903.]  CLIMATE  OF  ILLINOIS.  71 

The  rainfall  for  the  northern  district  is  33.48  inches,  the  least  being 
21.46  inches  in  1891,  the  greatest  being  47.22  inches. 

Seventeen  and  four- tenths  percent  of  the  rain  falls  in  winter,  28.1 
percent  in  spring,  31.9  percent  in  summer,  and  22.6  percent  in  autumn. 
May  is  the  wettest  month. 

The  rainfall  of  the  central  district  is  38.01  inches.  The  least  rainfall 
was  22.85  inches  in  1879,  the  greatest,  48.67  inches,  in  1876.  .  Eighteen 
and  eight-tenths  percent  of  the  total  rainfall  occurs  in  winter,  29.7 
percent  in  spring,  28.9  percent  in  summer,  and  22.6  percent  in  autumn. 
May  has  heaviest  rainfall. 

The  rainfall  of  the  southern  district  is  42.19  inches.  The  least  was 
30.05  inches  in  1872,  the  greatest,  55.68  inches,  in  1882.  About  21.6 
percent  falls  in  winter,  30.6  percent  in  spring,  26  percent  in  summer,  and 
21.8  percent  in  autumn.  March  has  most  rain. 

The  average  rainfall  for  the  state  is  37.39  inches.  The  least  was 
25  inches  in  1901,  the  greatest,  47.39  inches,  in  1898.  Six  northern 
counties  have  11.3  inches  less  than  seven  southern  counties.  The  Ozark 
Ridge  in  the  southern  part  of  the  state  makes  the  rainfall  of  the  counties 
in  which  it  is  situated  7.15  inches  more  than  those  immediately  above 
the  ridge.  A  rainy  region  is  situated  along  the  Wabash  River  up  as 
far  as  Crawford  County.  The  average  temperature  for  the  state  is 
52.3°  F.  Northern  tier  of  counties  46.9°,  southern  counties  57.6°. 
Northern  summers  are  7°  cooler  than  southern,  while  northern  winters 
are  17.2°  cooler. 

The  average  temperature  for  the  northern  district  is  48.9°.  January 
is  the  coldest  month,  22.1°,  July  is  the  hottest,  74.6°.  Lowest  tempera- 
ture recorded  31°  below  zero.  The  extreme  range  of  temperature  is 
143°,  average  annual  range  about  115°.  Highest  temperature  in  summer 
of  1901. 

The  average  temperature  for  the  central  district  is  52.7°,  the  extreme 
range  being  139°;  the  average  annual  range  being  about  109°.  Lowest 
temperature  recorded  was  28°  below  zero  in  1884,  highest  112°  in 
1901. 

The  average  temperature  for  the  southern  district,  55.9°.  Lowest 
temperature  observed  was  23°  below  zero^  in  February,  1899,  the  highest 
being  115°  in  1901.  Extreme  range  is  138°,  with  average  annual  range 
about  103°. 

The  average  date  for  the  last  killing  frost  in  spring  is  15  days  later 
in  northern  than  in  southern  part,  and  the  date  for  the  first  killing  frost 
in  fall  is  12  days  earlier  than  in  the  southern.  The  difference  between 
dates  of  last  killing  and  first  killing  frosts  for  extreme  parts  of  state 
is  40  days. 

November,  December,  January,  February,  March,  and  April  are  the 
cloudy  months  of  the  year,  being  cloudy  for  56  percent  of  the  daylight 


72 


BULLETIN  No.  86. 


[June, 


in  the  northern,  53£  in  each  of  the  other  sections.  The  other  months  of 
the  year  are  less  cloudy,  having  45^'  percent  in  the  northern,  40^  in  the 
central,  and  42  percent  in  the  southern.  December  is  the  cloudiest  month 
for  the  northern  and  southern  parts,  and  March  for  the  central  part. 

METEOROLOGICAL  SUMMARY  FOR  THE  EXPERIMENTAL  STATION. 


1889. 

TEMPERATURES. 

Rainfall 
in 
inches. 

Rela- 
tive 
humid- 
ity. 

Prevailing 
wind, 
directions. 

No.  of 
clear 
days. 

No.  of 
partly 
cloudy 
days. 

No.  of 
cloudy 
days. 

12 
4 
6 
4 
6 
4 
3 

8 
4 
14 

8 

Max. 

Min. 

Mean. 

Jan  

57 
53 
72 
75 
91 
88 
90.5 
89 
87.5 
82 
62 
66 

-2 
-7.5 
18 
25 
28 
40 
50 
29.5 
32 
25 
4 
15 

29.28 
23.36 
39.92 
51.9 
59.2 
65.5 
72.7 
69.2 
61.32 
47.26 
36.82 
42.71 

1.48 
2.08 
1.61 
.61 
5.52 
6.81 
5.81 
0.60 
2.74 
1.42 
4.38 
1.82 

79.1 
78.7 
78.5 
69.7 
74.9 
79.3 
80.0 
78.2 
80.1 
75.2 
83.4 
82.6 

S.  W. 
S.  W.  &  n.  W. 
n.  w. 
n.  e.  &  n.  w. 

s.  w. 
s.  w. 
s. 
s. 
s.  w. 
n.  w. 
n.  w. 
s.  w. 

6 

7 
10 
8 
1 
4 
8 

1 
15 
6 

8 

13 

,17 

15 

18 
24 
22 
20 

is 

12 
10 
15 

Feb  .  . 

March  .  .  . 
April  .... 
May  

June  .... 
July 

August.  .  . 
Sept  
Oct.  . 

Nov  
Dec  

Totals  .  .  . 

34.88 

y 

80 
7.3 

177 
16.1 

7a 

6.6 

Average  . 

76 

21 

49.9 

2.91 

78.3 

s.  w. 

1890. 
Jan  

66 
68 
61 
81 
83 
96 
97.5 
96 
89 
76 
68 
58 

-5 

7 
2 
29 
33 
47 
45 
44.5 
33 
27 
21 
8 

33.5 
34.66 
33.35 
52.32 
58.27 
74.56 
73.02 
68.74 
60.46 
52.07 
42.62 
30.91 

5.26 
1.87 
2.70 
4.11 
3.56 
3.80 
2.83 
1.93 
1.19 
2.35 
1.63 
.05 

88.0 
85.6 
79.2 
73.1 
72.2 
77.4 
77.9 
71.9 
76.8 
79.2 
74.6 
75.1 

n.  w. 
s.  w.  &  n.  w. 
n.  w. 
n.  e. 
s.  w. 
s.  w. 
n.  e. 
n.  w. 
n.  e. 
n.  w. 
n.  w. 
n.  w. 

6 
6 
8 
10 
14 
13 
17 
15 
6 
3 
10 
7 

15 
12 
16 
15 
14 
16 
13 
15 
20 
21 
12 
17 

10 
10 
7 
5 
3 
1 
1 
1 
4 
7 
8 
7 

Feb  
March  .  .  . 
April  .... 
May  

June  .... 
July 

August.  .  . 
Sept  
Oct  
Nov  
Dec  

Totals  .  .  . 

31.28 

115 
9.7 

186 
15.5 

64 
15.3 

Average  . 

78.2 

24.6 

51.2 

2.6 

77.6 

n.  w. 

1891. 
Jan.  . 

57 
61 
65 
81 
91 
93 
93 
99 
96 
88.5 
67 
60 

6 
-9 
-1 
22 
30 
49 
42 
40 
41 
27 
2 
11 

30.26 
30.45 
32.55 
52.78 
58.4 
71.9 
70.12 
70.21 
69.2 
51.3 
35.69 
37 

0.99 

2.60 
3.55 
3.54 
0.89 
2.08 
1.41 
2.86 
.41 
1.29 
5.58 
1.53 

84.7 
81.5 
84.9 
79.5 
70.0 
78.5 
79.6 
74.0 
66.0 
72.9 
83.1 
79.2 

s.  w. 
n.  w. 
n.  e.  &  n.  w. 
n.  w. 
n.  e. 
s.  w. 
s.  w. 
n.  w. 
s. 
s. 
s. 
s. 

6 
6 
4 
8 
12 
9 
11 
2 
6 
13 
6 
8 

10 
11 
16 
18 
14 
15 
18 
27 
23 
17 
13 
17 

15 
11 
11 
4 
5 
6 
2 
2 
1 
1 
11 
6 

Feb  
March  .  .. 
April  .... 
May  

June  .... 
July  

August.  .  . 
Sept  
Oct. 

Nov. 

Dec  
Totals  .  .  . 

26.73 

92 
7.6 

199 
16 

75 
6.1 

Average  . 

79.3 

21 

50.82 

2.22 

77.8 

s.,  s.  w. 

1903.] 


CLIMATE  OF  ILLINOIS. 


73 


METEOROLOGICAL  SUMMARY  FOR  THE  EXPERIMENT  STATION — Continued. 


1892. 

TEMPERATURES. 

Rainfall 
in 
inches. 

Rela- 
tive 
humid- 
ity. 

Prevailing 
wind, 
directions. 

No.  of 
clear 
days. 

No.  of 
partly 
cloudy 
days. 

No.  of 
cloudy 
days. 

Max. 

Min. 

Mean. 

Jan.  . 

57 
55 
69 
70.5 
82 
94 
96.5 
94 
87 
88.5 
64 
60 

-15 

*. 
* 

26" 
36 
51 
46 

47 
42 
19 

7 
_7 

19.2 
33 
36.1 
48.6 
57.9 
70.6 
73.3 
71.5 
63.9 
53.6 
34.8 
27.7 

0.79 
2.64 
2.59 
6.45 
7.86 
5.36 
2.50 
2.45 
0.93 
0.93 
4.95 
1.62 

82.9 
87.6 
82.1 
77.4 
81.1 
82.1 
80.4 
81.1 
76.3 
70.5 
83.7 
86.7 

s. 
s. 
s.  w. 
n.  w. 
s.  w. 
s.  w. 
s. 
w. 
s. 
s. 
s. 
s. 

6 
2 
3 
3 
1 
8 
4 
10 
14 
9 
7 
4 

20 
14 
22 
24 
23 
20 
24 
18 
15 
20 
16 
16 

5 
13 
6 
3 
7 
2 
3 
3 
1 
2 
7 
11 

Feb  
March  .  .  . 
April  .... 
May  

June  .... 
July 

August.  .  . 
Sept  
Oct  

Nov  
Dec  

Totals  .  .  . 

39.05 

- 

71 
5.9 

232 
19.3 

63 
5.3 

Average  . 

76.4 

49.1 

3.25 

81.0 

s. 

1893. 
Jan.  . 

48 
51 
76 
75 
84 
93 
98 
96 
97 
84 
75 
63 

*. 
*. 
*'.  '. 
30" 
37 
53 
48 
37 
31 
18 
6 
-6 

14.8 
25.8 
37.8 
49.3 
57.4 
70.5 
76.4 
71.1 
66.5 
53.3 
37.3 
30 

1.05 
4.48 
3.20 
7.68 
4.83 
1.55 
.59 
.06 
3.62 
1.14 
2.98 
1.09 

86.1 
87.5 
79.6 
76.0 
75.6 
70.5 
71.9 
66.8 
58.6 
77.4 
84.8 
84.4 

n.  w. 
n.  w. 

s. 
s. 
n.  &  s.  w. 
s. 
s. 
n. 
w. 
s. 
s. 
s. 

4 
5 
2 
1 
4 
6 
1 
11 
4 
9 
6 
0 

17 
14 
22 
19 
24 
18 
29 
19 
19 
18 
16 
18 

10 
9 
7 
10 
3 
6 
1 
1 
7 
4 
8 
13 

Feb  
March  .  .  . 
April  .... 
May  

June  .... 
July  

August.  .  . 
Sept  
Oct  

Nov  
Dec  

Totals  .  .  . 

32  37 

53 

4.4 

223 
19 

79 
6.5 

Average  . 

78 

49.1 

2.69 

76.6 

s. 

1894. 
Jan.  . 

64 
58 
77 
85 
89 
97 
98 
99 
94 
84 
67 
59 

-21 
-5 
10 
25 
32 
34 
47 
41 
38 
28 
12 
-4 

29.4 
24.7 
43.5 
51.4 
59.6 
73.4 
73.8 
72.3 
65 
51.9 
35.9 
32.9 

1,95 
1.32 
2.41 
1.86 
3.32 
1.78 
1.08 
2.06 
4.21 
.51 
2.77 
1.44 

84.4 
81.2 
83.5 
78.6 
80.7 
75.4 
68.9 
72.2 
84.6 
79.7 
84.2 
86.2 

s. 
w. 

s. 
s. 
s. 
s. 
s. 
w. 
s. 
s. 
s. 
s. 

3 
1 
4 
1 
3 
5 
4 
6 
10 
5 
3 
6 

18 
19 
21 
22 
25 
24 
27 
25 
15 
21 
18 
17 

10 
8 
6 
7 
3 
1 
0 
0 
5 
5 
9 
8 

Feb  
March  .  .  . 
April  .... 
May  

June  .... 
July  . 

August.  .  . 
Sept  
Oct.  . 

Nov.  . 

Dec  
Totals  .  .  . 

24  72 

51 

4.2 

252 
21 

62 
5.1 

Average  . 

81 

19.7 

51.1 

2.06 

79.9 

s. 

*  Record  incomplete. 


74 


BULLETIN  No.  86. 


[June, 


METEOROLOGICAL  SUMMARY  FOR  THE  EXPERIMENT  STATION — Continued 


1895. 

TEMPERATURES. 

Rainfall 
in 
inches. 

Rela- 
tive 
humid- 
ity. 

Prevailing 
wind, 
directions. 

No.  of 
clear 
days. 

No.  of 
partly 
cloudy 
days. 

No.  of 
cloudy 
days. 

Max. 

Min. 

Mean. 

Jan  
Feb  
March  .  .  . 
April  .... 
May  

57 
53 
84 
88 
95 
98.5 
94 
97 
87.5 
82 
62 
66 

-2 
7.5 
7 
27 
28 
42 
43 
48 
32 
25 
4 
15 

29.28 
23.36 
35.9 
52.3 
59.4 
73.3 
71.3 
73.2 
61.32 
47.26 
36.82 
42.71 

1.36 
.52 
.70 
2.42 
2.20 
2.24 
3.61 
1.81 
5.27 
.21 
3.07 
5.71 

93.3 
91.7 
83.3 
78.0 
71.2 
67.0. 
75.8 
72.2 
75.0 
65.2 
81.1 
87.5 

n.  W. 
n.  w. 
n.  w. 
n.  e. 

s. 
s. 
s. 
s. 
s. 
n.  w. 
s. 
s. 

9 
8 
7 
7 
14 
10 
5 
6 
12 
14 
3 
2 

14 
17 
17 
17 
16 
18 
22 
21 
15 
15 
14 
13 

8 
3 
7 
6 
1 
2 
4 
4 
3 
2 
13 
16 

June  .... 
July  

August.  .  . 
Sept.  . 

Oct  

Nov  
Dec  

Totals  .  .  . 

29.12 

97 

8 

199 
16 

69 

5.7 

Average  . 

80.3 

18.7 

55.1 

2.42 

78.4 

s. 

1896. 
Jan.  . 

52 
68 
67 
86 
91 
92 
95 
97 
91 
79 
74 
62 

-5 
-4 
6 
21 
45 
49 
49 
44 
30 
24 
9 
8 

28.1 
29.6 
34.4 
57.6 
68.2 
70.2 
73.8 
72 
61.9 
48.8 
39.9 
33.3 

1.12 
1.95 
1.22 
1.89 
5.62 
2.98 
7.87 
3.74 
5.84 
.42 
2.87 
.39 

89.6 
81.8 
83.0 
70.6 
76.2 
78.4 
76.3 
80.0 
81.4 
78.6 
87.9 
87.0 

s. 
s.  w.  &  n.  w. 

n.  w. 

s.  w. 
s. 
s. 
s. 
s. 
s. 
n. 
s. 
s.  w. 

2 
3 
5 
10 
7 
1 
5 
12 
5 
18 
6 
3 

13 
14 
19 
19 
19 
24 
19 
17 
14 
9 
13 
20 

16 
12 
7 
1 
5 
5 
7 
2 
11 
4 
11 
8 

Feb  
March  .  .  . 
April  .... 
May  

June  .... 
July  

August.  .  . 
Sept  
Oct.  . 

Nov  
Dec  

Total  . 

35  91 

77 
6.4 

200 
16 

89 
7.4 

Average  . 

79 

23 

51.4 

2.92 

80.9 

s. 

1897. 
Jan.  . 

59 
59 
66 
79 
83 
93 
98 
97 
97.5 
92 
69 
59 

-15 
-2 
20 
21 
31 
44 
53 
42 
32 
32 
11 
1 

22 
30 
40 
48 
58 
69.5 
75.8 
70.0 
69.4 
59.1 
39.5 
26.3 

4.53 
1.17 
4.10 
3.69 
1.8-1 
5.16 
4.68 
0.63 
0.31 
0.42 
4.91 
2.67 

95 
90 
88 
82 
77 
79 
80 
79.2 
68.5 
71.0 
86.8 
93.7 

n.  w. 
n.  w.  &  n. 

s.  e. 
s.  w. 
n.  w. 
s.  e. 
w.  &  n.  w. 
n.  w. 
s.  w. 
s.  &  s.  e. 
n.  w. 
n.  w. 

10 
3 
3 
3 
6 
1 
10 
13 
24 
20 
9 
2 

10 
16 
17 
14 
21 
7 
12 
16 
5 
8 
10 
16 

11 
9 
11 
13 
4 
22 
9 
2 
1 
3 
11 
13 

Feb  
March  .  .  . 
April  .... 
May  

June  .... 
July  .  . 

August  .  . 
Sept  
Oct  

Nov  
Dec  

Total  . 

34  08 

104 

8.7 

152 
12.5 

109 
9.1 

Average  . 

79.3 

22.5 

50.6 

2.84 

82.5 

n.  w. 

1903.] 


CLIMATE  OF  ILLINOIS. 


75 


METEOROLOGICAL  SUMMARY  FOR  THE  EXPERIMENT  STATION — Continued. 


1898. 

TEMPERATURES. 

Rainfall 
in 
inches. 

Rela- 
tive 
humid- 
ity. 

Prevailing 
_wind, 
directions. 

No.  of 

clear 
days. 

No.  of 
partly 
cloudy 
days. 

No.  of 
cloudy 
days. 

Max. 

Min. 

Mean. 

Jan.  . 

62, 
65 
69 

79 
82 
90 
96 
94 
94 
86 
68 
55 

5 
-6 
15 
22 
38 
49 
47 
53 
45 
40 
*. 

*!  '. 

30.8 
30.3 
39.4 
48.5 
61.5 
73.6 
76.9 
74.0 
68.2 
51.4 
36.1 
26.8 

4.77 
1.43 
7.76 
2.71 
5.65 
6.08 
1.89 
3.61 
5.13 
4.53 
3.01 
1.86 

87.7 
94.2 
90.2 
77.3 
83.3 
80.5 
78.0 
84.0 
85.3 
86.9 
88.8 
96.0 

W. 

n.  w. 
n.  w. 
n.  w. 

s.  w. 
s.  w. 
s.  w. 
s.  w. 
s.  w. 
s. 
s.  w. 
n.  w. 

6 
3 
6 
3 
4 
8 
13 
9 
4 
4 
11 
10 

11 
7 
17 
20 
16 
17 
6 
18 
21 
17 
11 
16 

14 
18 
8 
7 
10 
5 
12 
4 
6 
10 
8 
5 

Feb  
March  .  .  . 
April  .... 
May  

June  .... 
July   . 

August.  .  . 
Sept  
Oct  

Nov  
Dec  

Total  .  .    . 

48  43 

81 
6.7 

177 
14.7 

107 
8.9 

Average  . 

78.3 

51.5 

4.03 

86.0 

s.  w. 

1899. 
Jan  

53 
58 
65 
90 
86 
93 
94 
96 
99 
87 
69 
60 

-12 
-25 
-2 
15 
42 
50 
51 
49 
24 
29 
17 
-6 

25.5 
18.4 
32.4 
53.1 
63.8 
71.4 
74.4 
75.3 
63.1 
57.2 
43.8 
27.8 

1.97 
2.33 
1.78 
0.50 
6.09 
2.29 
2.65 
2.29 
1.07 
5.10 
"1.39 
2.14 

96.4 
96.4 
94.1 
89.3 

82.5 
78.3 
79.3 
77.2 
74.6 
78.0 
88.5 
87.6 

s.  w. 
s.  w. 
n.  w. 
s.  w.  &  s. 
s.  w. 
s.  &  s.  w. 
s.  w. 
s.  w. 
s.  w. 
s.  w. 
n.  e.  &  s.  w. 
n.  w. 

5 
6 
5 
5 
3 
3 
7 
15 
11 
6 
0 
0 

19 
16 
10 
20 
19 
25 
19 
11 
14 
17 
19 
17 

7 
6 
16 
5 
9 
2 
5 
5 
5 
8 
11 
14 

Feb  
March  .  .  . 
April 
May.  . 

June  .... 
July  

August.  .  . 
Sept  
Oct  

Nov  
Dec  

Total  .  .    . 

29.60 

66 
5.5 

206 
17.2 

93 

7.8 

Average  . 

79.2 

19.3 

50.5 

2.47 

85.2 

s.  w. 

1900. 
Jan  

61 
63 
61 

83 
89 
90 
93 
95 
93 
88 
72 
58 

-5 

-6 
0 
24 
33 
47 
51 
63 
34 
32 
12 
1 

30.1 
24.0 
32.6 
51.2 
63.3 
69.3 
74.2 
78.4 
68.2 
59.9 
39.6 
29.9 

0.17 
3.59 
1.79 
0.84 
4.60 
4.11 
3.81 
6.23 
2.23 
2.29 
3.42 
1.00 

92.9 
91.2 
90.7 
74.9 
74.6 
82.1 
79.4 
80.0 
78.7 
77.6 
65.7 
73.9 

w. 

n.  w. 
n.  w. 
n.  e. 

s.  w. 
n.  e. 
s.  w. 
s. 
s.  e.  &  s.  w. 
s.  e. 
s.  w. 
s.  w. 

1 
0 
0 
3 
1 
0 
2 
4 
1 
1 
0 
2 

20 
16 
17 
16 
24' 
21 
5 
26 
24 
25 
22 
21 

10 
12 
14 
11 
6 
9 
24 
1 
5 
5 
8 
8 

Feb  
March  .  .  . 
April  .... 
May  

June  .... 
July  .  . 

August.  .  . 
Sept  
Oct  

Nov  
Dec  

Total  

34.08 

15 

1.2 

237 
19.7 

113 

9.4 

Average  . 

78.8 

23.9 

51.7 

2.84 

80.1 

s.  w. 

*  Record  incomplete. 


76 


BULLETIN  No.  86. 


[June,  1903.] 


METEOROLOGICAL  SUMMARY  FOR  THE  EXPERIMENT  STATION — Continued. 


1901. 

TEMPERATURES. 

Rainfall 
in 
inches. 

Rela- 
tive 
humid- 
ity. 

Prevailing 
wind, 
directions. 

No.  of 
clear 
days. 

No.  of 
partly 
cloudy 
days. 

No.  of 
cloudy 
days. 

Max. 

Min. 

Mean. 

Jan.  . 

61 
47 
70 
87     , 
89 
95 
104 
101 
94    • 
88 
69 
60 

-7 
-2 
5 
28 
38 
44 
48 
54 
33 
29 
16 
-15 

27.8 
21.0 
37.6 
48.5 
59.2 
72.2 
79.5 
73.8 
64.6 
53.5 
35.8 
24.2 

1.55 
1.41 
3.14 
0.80 
1.93 
5.80 
2.48 
1.68 
1.38 
4.10 
1.31 
3.06 

92.6 
92.1 
85.2 
72.7 
82.1 
77.9 
77.4 
69.7 
75.6 
76.4 
80.5 
88.8 

n.  w. 
n.  w. 
s.  w. 
s.  e. 
n.  e. 
s.  w. 
s.  w. 
n.  e. 
s.  w. 
s.  w. 
n.  w. 
n.  w. 

0 
1 
0 
4 
2 
2 
2 
2 
4 
6 
0 
0 

16 
21 
12 
13 
21 
25 
29 
26 
22 
19 
25 
16 

15 
6 
19 
13 
8 
3 
0 
3 
4 
6 
5 
15 

Feb  
March  .  .  . 
April  .... 
May  

June  .... 
July  

August.  .  . 
Sept  
Oct.  .  . 

Nov  
Dec  

Total  

28  64 

23 
1.9 

245 
20.4 

97 
8.1 

Average  . 

80.4 

22.7 

49.8 

2.39 

80.9 

s.  w. 

1902. 
Jan.  . 

56 
48 
70 
85 
90 
92 
91 
90 
84 
78 
75 
51 

-7 
-14 
9 
23 
40 
45 
50 
52 
34 
31 
14 
0 

25.7 
16.8 
40.8 
48.1 
65.8 
68.4 
74.6 
69.4 
61.7 
54.5 
46.6 
27.0 

0.62 
1.48 
1.69 
2.11 
2.60 
*11.73 
4.02 
9.80 
4.90 
2.10 
2.42 
2.94 

83.5 
86.3 
81.4 
73.9 
75.0 
78.1 
77.1 
80.1 
82.5 
80.8 
83.0 
89.3 

n.  w. 
n.  w. 
s.  w. 
s.  w.  &  n.  w. 

s.  e.  &  s.  w. 
s.  w. 
s.  w. 
s. 
s. 
s.  w. 
s.  w. 
s.  w. 

0 
1 
0 
0 
2 
1 
13 
6 
3 
1 
0 
1 

25 
21 
18 
26 
25 
21 
14 
19 
15 
24 
18 
15 

6 
6 
13 
4 
4 
8 
4 
6 
12 
6 
12 
15 

Feb  
March  .  .  . 
April  .... 
May  

June  .... 
July  

August.  .  . 
Sept  
Oct  

Nov  
Dec  

Total  

46.41 

28 
2.3 

241 
20.1 

96 

8 

Average  . 

75.9 

23.1 

49.9 

3.87 

80.9 

s.  w. 

*  The  storm  during  the  night  of  June  10  blew  the  rain-gauge  over,  but  .75  inch 
is  included,  which  was  about  the  rainfall  during  the  storm. 

- 


UNIVERSITY  OF  ILLINOIS-URBANA 


